In a previous woodlands.co.uk blog, Professor  Dave Goulson (University of Sussex) has written about the problems that bees and bumblebees face.  Recently, he joined with Clipper teas (who produce organic tea products) to again emphasise the problems that bees and other pollinators face, and to explain how our lives would be affected if they were to be lost.  Bee, bumblebee and other pollinator populations are at risk or in decline.  Professor Goulson estimates that there are some 6,000 different species of pollinating insects in the U.K alone, but they face risks as a result of Habitat loss Pollution Climate change Use of pesticides (insecticides, herbicides, fungicides) [caption id="attachment_36158" align="aligncenter" width="650"] Hoverfly foraging[/caption] Whilst it is true that insecticides such as neonicotinoids are directly toxic to bees and bumblebees, many other compounds used as herbicides and fungicides are also harmful to these insects.  Obviously herbicides get rid of weeds, but weeds or wild flowers are a food source for these pollinators.  Pesticides can have what are termed  ‘sub-lethal effects’, so that the learning ability of the insects is reduced.  Bees and bumblebees can learn which flowers are best as food sources, they can navigate to and from their nests / hives through open countryside.  Also these compounds can affect their resistance to disease, and their fertility / reproduction. It is a concern that that bees’ honey stores may contain a cocktail of several pesticides that the bees have encountered during their foraging.  In collecting pollen and nectar, a single bee may visit / pollinate four thousands flowers in a day. Not only are many thousands of  wild flowers species dependent on bees for pollination but some three quarters of our food crops also need bees and other insects.  Without them, the range and availability fo fruit and vegetables in our supermarkets would be substantially reduced. Whilst going organic and reducing reliance on the many forms of pesticide agriculturally is great help to pollinators, there is also good news in that small growers and even domestic gardeners can have a positive impact on the numbers of bees and others pollinators, such as : Planting a range bee-friendly plants in their gardens Creating a wild flower area in the garden or Allowing the lawn to grow up to form a small meadow like area Reducing the use of all pesticides - insecticides, herbicides, fungicides etc.

Pesticides problems. The effect of pesticides on bees and bumble bees is now well documented.  However, the combined effect of different pesticides is less well known.  If pesticide A is known to kill 10% of the bees in an area that has been treated, and pesticide B kills another 10% then it might be reasonable to assume that 20% of the bees would be killed - IF the effects are additive.  However, evidence is beginning to indicate that the effects of the pesticides is more than the sum of the parts - the pesticides work together / synergistically. Pesticide formulations that are sold to farmers are often ready mixed ‘cocktails’ so exposure to more than one pesticide is often the norm,  so it is important that these co-operative effects are understood and known. Honey bees have been affected by not only pesticides but also varroa.  Varroa is a mite, which lives and feeds on honeybees and their larvae.  Fortunately, bees have complex hygienic behaviours, for example, removing dead larvae or pupae.   Research indicates that honey bees are modifying this behaviour to deal with varroa mites. Helping pollinators Researchers at the University of Freiburg have recently published work establishing the importance of semi-natural habitat regions next to orchards and other agricultural landscapes for pollinators.  Such areas (ditches, banks, overgrown fences etc) help ensure that flowers (and therefore nectar and pollen) are available over a significant period of time.  This is important for pollinators such as hover flies, solitary bees, bumblebees etc. as nectar / pollen provided by crops is only available for a short and limited period.  Such areas are also important for overwintering, nesting sites, providing food for larval stages etc).  Their work focused on orchards near Lake Constance in Southern Germany. Soil remediation with lupins. There are many sites around the world where the soil is contaminated with metals (such as arsenic) as a result of past mining / industrial activities.  Such arsenic contaminated soil might be ‘revived’ by using the natural mechanisms that some plants have evolved to deal with certain contaminants.   The white lupin (Lupinus alba) is an arsenic-tolerant plant that might be a candidate for phytoremediation of soil.  The tolerance of the white lupin to arsenic is thought to be due to the release of chemicals by the roots into the soil.  Staff at the University de Montréal placed nylon pouches close to the roots to capture the molecule released.  The chemicals were then analysed to see which could bind to the arsenic (phytochelatins).  Phytochelatins are known to be used within plants to deal with metals but here they seem to be used externally.  Quite how they work is yet to be determined.

The vibrancy and gaudiness of sunflowers is one of the delights of summer.  The common name "sunflower" generally refers to Helianthus annuus, whose round flower heads look like the sun.  Sunflowers are cultivated as food crops for humans, cattle, and poultry, and also for the garden. They typically grow during the summer and into early autumn, with the peak growth season being mid-summer. A field of sunflowers is a welcome relief from the acres of oilseed rape. The flower of a sunflower is not a flower but hundreds of small flowers (florets) massed together the better to attract pollinators.  The structure so formed is known as a capitulum.  The inner florets are arranged in spirals that conform to fibonacci sequences.  The pattern of these florets has been described mathematically by Helmut Vogel and it allows for the most efficient ‘packing’ of the florets in the ‘flower’ head. Before the flowers open,  the plants tilt during to face the sun, gaining more light for photosynthesis. This movement is known as heliotropism  and continues for a while when the flower head opens. This may help to attract pollinators.  Frequent visitors to sunflowers are bumblebees.  Sadly, like honey bees, bumblebees face a number of problems which include parasites.  However, recent research in the United States suggests sunflowers can help certain species of bumblebee.  If sunflower pollen is included in the diet of the common eastern bumblebee then it helps reduce infection by a parasitic protozoan Crithidia bombi.  This is a parasite that lives in the gut of bumblebees. When they pass out of the gut in cysts, they can be ‘picked up’ by the next passing bumblebee (or another insect, as the parasite is not too fussy). Once established in a bee, the parasite can affect the ovaries.  If a  queen is infected then the reproductive success of the colony is affected. Giacomini et al. have found that good nutrition is vital for bumblebee health and that sunflower pollen can be a huge benefit when it is included in the diet. They noted that the majority of the bees that consumed sunflower pollen had no detectable infection a week later. The pollen* significantly reduced infection by the parasite. So sunflowers are a visual feast for us, and an edible one for bumblebees and bees.  They also provide us with seeds.  The seeds are rich in monounsaturated and polyunsaturated fats, notably linoleic acid. The seeds also contain phytosterols which may contribute toward lowering the level of blood cholesterol.  The seeds may be pressed releasing sunflower oil, and the remaining ‘cake’ can be used as a protein rich animal feed.  The Ukraine and Russia are the top producers of sunflower seed. A somewhat different use of sunflowers is phytoremediation; using plants to remove toxic organic or inorganic compounds from soil.  After the disaster at the Chernobyl nuclear reactors in 1986, an exclusion zone with a radius of 30 km centred on the nuclear power plant was created. This was later expanded to include other heavily irradiated areas.  Even now, no one lives in the exclusion zone, but scientists and others may ask for permits to allow them to enter for short periods.  Fields of sunflowers were planted to ‘harvest‘ the radioactive metals (notably caesium-137 and strontium-90) from the soil. The sunflowers accumulated these elements in their tissues.  When the sunflowers had completed their growth, they were harvested and burnt, leaving only the radioactive ash behind. This material could then be vitrified (incorporated into glass) and stored underground in a shielded container. In Brazil, a study looked at the ability of different sunflower cultivars to remove nickel, copper and lead from contaminated soil.  Though phytoremediation with sunflowers proved to be an efficient and low-cost method for the treatment of contaminated soils, the cultivars varied in their ability to take up particular metals. “Cleaning up’ with sunflowers was tried after a tsunami hit the Fukushima Daiichi nuclear power station in Japan.  However, it was not very successful.   As different cultivars vary in their capacity to hyperaccumulate, so it is important to match the cultivar to the situation. Planting sunflowers in this case did little to improve the situation. This could be in part due to the sunflowers but also be associated with the soil type and the time that the caesium has had to bind to the soil particles. Understanding the mechanisms and detail of hyper accumulation is critical if sunflowers are to be used for phytoremediation in the future. Pollen is rich in secondary plant metabolites e.g. flavonoids, terpenoids, alkaloids, amines, and chlorogenic acids [caption id="attachment_35695" align="aligncenter" width="650"] field of sunflowers[/caption]  

Humidity and bumblebees Recent research at the University of Bristol has shown that bumblebees are sensitive to the humidity of the air that surrounds flowers.  Being able to detect this sensory information affects the bees’ behaviour. Just as bees learn to recognise patterns, colour and the scent of particular flowers so they can distinguish humidity patterns.   How effective these humidity patterns are will depend on the immediate micro-environment of a flower - which may be affected by climate change.   Full details of this work can be accessed here : Willows and waste water Read more...

Recent years have seen periods of very hot temperatures, often resulting in forest or moorland fires.  Such extreme weather events have been seen not only in the UK but across the globe (Arizona , Victoria Australia, Indonesia).    Whilst spells of extreme heat (and drought) have been known throughout history,  it would seem that such events have become more common in recent years.   The first years of the 21st century are among the warmest on record  and this warming is associated with increasing levels of greenhouse gases (due to human activity).   Prolonged heat is not without its effects on us.  The very young and the elderly are most at risk from ‘heat waves’.  The 2003 heatwave across Europe is said to have caused several thousand  'excess' deaths’, mainly of the elderly].  However, heat affects nearly every living organism,  several of the woodlands blogs have written about the effects of drought, one of the effects of prolonged or intense temperatures.  Now research by Wageningen University has looked at some of the effects of rising temperatures on insects.  Concern about the decline of insect populations has resulted in headlines like ‘insect apocalypse or insect armageddon’. Read more...

Climate change is affecting all parts of the world, from the melting of the ice caps in Antarctica, to droughts in Australia and California.  On a more local level, we may see changes in our rainfall pattern.  Certainly for many parts of the UK, it has been a very dry start to the Spring, coupled with some very cold nights. Cold and dry weather affects plant growth in significant ways.  Warmth is needed for a plant’s enzymes (catalysts) to work, speeding up reactions and allowing growth.  Similarly, if water is in short supply, growth is stunted.   Plants do not realise their full ‘potential’, they are smaller overall as is the number and size of flowers that they produce.  Flowers attract visitors by colour, size and scent; or combinations thereof.   Smaller and fewer flowers, in turn, have ‘knock-on effects’ for their pollinators - bees, bumble bees, hoverflies etc. Read more...

Much of England experienced a series of ‘tropical nights’ last summer, when night time temperatures were 20oC or above.  These tropical nights were associated with the heat wave that affected most of south east England.  Central London experienced its longest stretch of extreme daytime temperatures since the 1960’s -  temperatures of 30+oC were recorded on six consecutive days.  A number of experts have said that such heatwaves and associated tropical nights are likely to become more common as a consequence of climate change.   We were not alone in experiencing high temperatures by day and night, much of western Europe  sweltered in the heat this August. The problem was most marked in urban areas and large cities.  Some three-quarters of the population of Europe now live in urban areas. Extreme heat affects our health causing general discomfort, malaise, respiratory problems, headaches, heat stroke, heat cramps and heat-related mortality.  Read more...

Primroses were said to be the favourite flower of Benjamin Disraeli, indeed he wrote of them that he liked primroses so much better for their being wild “they seem an offering from the fauns and dryads of the woods”.  On his death, Queen Victoria sent a wreath of primroses to his funeral with a note ‘his favourite flower’ (though it is not clear whether this referenced Disraeli or her late husband - Albert). Primroses are generally regarded as the harbingers of Spring, indeed the name Primrose comes from the latin for first rose - Prima Rosa. In different parts of the country, the primrose sometimes has other names such ‘Easter Rose’, ‘Lent Rose’ and ‘Early Rose’.  Its scientific name is Primula vulgaris. Read more...